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Utilization of Ternary Europium Complex for Organic Electroluminescent Devices and as a Sensitizer to Improve Electroluminescence of Red-Emitting Iridium Complex
摘要： Two new lanthanide complexes [Ln(hfaa)3(Py-Im)] [hfaa = hexafluoroacetylacetone, Py-Im = 2-(2-pyridyl)benzimidazole and Ln = Eu(III) (1) and Tb(III) (2)] were synthesized and characterized. An X-ray crystal structure determination confirms that complex 1 is eight-coordinate with a distorted trigonal dodecahedral geometry. It shows typical vivid red Eu(III) emission in the solid state, in solution, and in a polymer matrix. The observed lifetime (τobs) of complex 1 in the solid state, in dichloromethane (DCM) solution, and in thin films is 833.01, 837.95, and 626.16?715.69 μs, respectively, with a photoluminescence quantum yield QEuL ≈ 33% in DCM solution. Complex 2 displays a yellowish-green emission in the solid state (τobs ≈ 36.99 μs), while a near white-light emission in solution (x; 0.2574: y; 0.3371) and in thin films. Therefore, it is a potential candidate for generating single-component white light-emitting materials for solid-state lighting applications. The kinetic scheme for modeling energy-transfer processes shows that the main donor state for 1 is the ligand triplet state (T1) and that energy transfer occurs to both the 5D1 (56.55%) and 5D0 (40.58%) levels. We fabricated a series of single- and double-layer organic light-emitting devices using complex 1. The luminance of the optimized double-layer electroluminescence (EL) device was 373 cd/m2 with very low turn-on voltage of ～4.2 V. Complex 1 was further utilized as a sensitizer to improve the EL of a red-emitting iridium complex PQ2Ir(dpm) (PQ = phenylquinoly-N,C2′, dpm = dipivaloylmethane). The codoped device achieved a maximum brightness and maximum current efficiency (ηc) of 93 224 cd/m2 and 36.38 cd/A, respectively.
关键词： electroluminescence,organic light-emitting devices,photoluminescence,energy transfer,lanthanide complexes
更新于2025-11-20 15:33:11
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Luminescent materials of covalent grafting lanthanide complexes to the synthetic clays
摘要： Lanthanide complex-based luminescent organic-inorganic hybrid materials are highly interesting for a broad range of application fields. The combination of lanthanide complexes with the synthetic clay, Laponite, is now attracting the interest of scientists due to the unique features of the synthetic clay. However, most of the reported literatures are involved with the adsorption of lanthanide complexes on the clay particles. Taking the covalent incorporation of lanthanide complex into clay and satisfying the further coordinate with central lanthanide ion into account, herein, we reported a facile strategy of covalent grafting lanthanide complexes to the clay via the reaction of the terminal triethoxy groups of triethoxysilylated ligand (phenSi) and the surface OH groups of the clay. The successful grafting of the complexes was confirmed by the FT-IR spectra, 29Si solid-state NMR spectra and the luminescent data. And the nitrogen atoms of Phen moieties which are covalently grafted to the clay provide the chance to prepare luminescent hybrid materials with larger coordination number.
关键词： covalent grafting,lanthanide complexes,Laponite,luminescent materials
更新于2025-11-14 15:18:02
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Lanthanide complexes with 2-(tosylamino)-benzylidene-N-(aryloyl)hydrazones - universal luminescent materials
摘要： Lanthanide complexes Ln(L1)(HL1) (Ln = Lu, Yb, Er, Gd, Eu, Sm) and Ln(L2)(HL2) (Ln = Lu, Yb, Gd, Eu) with 2-(tosylamino)-benzylidene-N-(aryloyl)hydrazones (H2L1, aryloyl = 2-hydroxybenzoyl; H2L2, aryloyl = Isonicotinoyl) were obtained with the aim to explore them as new luminescent materials. They were found to form monomeric species independently on the aryloyl nature, their crystal structures were determined from single crystal X-ray data (Yb(L2)(HL2)·0.5(C2H5OH)), as well as from powder X-ray data by Rietveld refinement (Eu(L1)(HL1)). Ytterbium complexes exhibited intense luminescence, which allowed using them in host-free OLEDs, which demonstrated remarkable efficiency of NIR electroluminescence (50 μW/W) at low voltage (5V). Special mechanism of europium luminescence quenching allowed using europium complexes as luminescent thermometers, which demonstrated very high sensitivity up to 12%/K. The theory of luminescence thermometry based on three-level system was proposed which allowed predicting sensitivity with high accuracy (error within 20%).
关键词： lanthanide complexes,OLEDs,luminescent thermometry,NIR emission,luminescent materials
更新于2025-09-23 15:23:52
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Quantitative Sensitization Efficiencies in NIR-Emissive Homoleptic Ln(III) Complexes Using 2-(5-Methylpyridin-2-yl)-8-hydroxyquinoline
摘要： A series of lanthanide complexes [Ln(MPQ)3] (Ln = Nd, Gd, Er, Yb, Lu) using a monoanionic tridentate methylpyridyl-substituted 8-hydroxyquinoline ligand (MPHQ = 2-(5-methylpyridin-2-yl)-8-hydroxyquinoline) have been prepared and characterized using elemental analysis (CHN), single-crystal X-ray diffraction (XRD), and 1H NMR spectroscopy. This ligand forms homoleptic charge-neutral lanthanide complexes with three coordinated ligands arranged in an 'up?up?down' fashion around the metal center. The photophysical properties of the Nd, Er, and Yb complexes were investigated using absorption and emission spectroscopy, with the latter species displaying efficient sensitization in the Near Infra-Red (NIR) region and a photoluminescence quantum yield (PLQY) as high as 1.0% in CH2Cl2 solution. The intersystem crossing and energy-transfer processes involved in the antenna effect were further investigated using transient absorption techniques, which revealed essentially quantitative sensitization efficiencies for the NIR-emitting cations.
关键词： lanthanide complexes,8-hydroxyquinoline ligand,homoleptic,quantitative sensitization efficiencies,NIR-emissive
更新于2025-09-23 15:21:01
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Modulation of the properties of dinuclear lanthanide complexes through utilizing different ?2-diketonate co-ligands: near-infrared luminescence and magnetization dynamics
摘要： A family of new dinuclear lanthanide complexes as the simplest entities showing intramolecular magnetic interactions, [Ln2(dbm)2(L)2(CH3OH)2] (Ln = Tb (1), Dy (2), Ho (3), Er (4), Yb (5), Lu (6)), [Ln2(acac)2(L)2(EtOH)2] (Ln = Dy (7), Er (8)), [Dy2(TTA)2(L)2(CH3OH)2]·2CH2Cl2 (9) and [Dy2(tfa)2(L)2(CH3OH)2] (10) (H2L = N’-(2-hydroxy-5-methylphenyl)-pyrazine-2-carbohydrazide, Hdbm = 1,3-diphenyl-1,3-propanedione, Hacac = acetylacetone, HTTA = 2-thenoyltrifluoroacetone, Htfa = trifluoroacetylacetone), were constructed successfully by the reaction of a Schiff base ligand H2L and four different β-diketonate salts. As for complexes 4, 5 and 8, all exhibit the characteristic emission peaks of the corresponding Er3+, Yb3+ and Er3+ ions, respectively. Meanwhile, the excitation wavelength (510 nm) of 5 is located in the visible region, confirming its significant potential application value. Magnetic studies indicate that complexes 9 and 10 exhibit characteristic slow relaxation of magnetization with the energy barriers (Ueff) of 102 K for 9 and 140 K for 10 under a zero dc field. Under the optimized dc fields, slow magnetic relaxations are present in 2 and 7, and the Ueff values of 9 and 10 have been improved. This proves that the β-diketonate co-ligands deserve an important role in regulating Dy-SMMs influenced by the diverse perturbations of the axial crystal field originating from minor changes in the coordination environment.
关键词： single-molecule magnets,dinuclear lanthanide complexes,β-diketonate co-ligands,near-infrared luminescence,magnetization dynamics
更新于2025-09-23 15:19:57
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Influence of nonradiative Auger process in the lanthanide complexes lifetime near interfaces in organic light-emitting diode structures
摘要： The low efficiency of organic light-emitting diodes based on lanthanide complexes is generally attributed to the triplet-triplet annihilation processes in the regime of high concentration of excited states caused by their long lifetimes and optical losses near the interfaces of multilayer device structures. Despite the enormous effort to synthesize short-lived complexes and minimize the optical losses in the interfaces, it remains insufficient in understanding the exciton recombination processes that reduce the lifetime of these complexes. Herein, we investigated the influence of the exciton recombination processes on a Tb complex (Tb-C) lifetime in the regime of a highly excited state concentration as a function of the distance between the carrier layer and the interface by using a typical organic light-emitting diode structure. Our results show that a 10 nm-thick Alq3 layer decreases the exciton lifetime of the Tb-C, increasing approximately by 16 times the spontaneous emission decay rate of triplet exciton. The effects of interference and optical losses at the metallic interface contribute actively to the modulation of the emission intensity and lifetime decay. However, these effects alone do not explain the significant increase in the emission decay rate. The nonradiative Auger process at the Alq3/Tb-C interface seems to be largely accountable for the Tb-C lifetime reduction as the energy released by the terbium ion occurs by the excitation of an adjacent electron at higher energy. Furthermore, we propose a simple theoretical model to explain the observed effects. These results can provide a new approach to reduce the lanthanide complexes’ lifetime through the Auger electron process near the interface and thus improve the performance of organic light-emitting diodes.
关键词： exciton recombination,Auger process,organic light-emitting diodes,lifetime reduction,lanthanide complexes
更新于2025-09-19 17:13:59
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Light-controlled efficient photoluminescence based on an europium β-diketonate complex with single-crystal-to-single-crystal [2+2] cycloaddition
摘要： A brand new europium(III) b-diketonate complex undergoes a single-crystal-to-single-crystal transformation via [2+2] cycloaddition after UV irradiation, triggering strong Eu(III) red emission turn-on, which is highly photostable even after 50 hours of irradiation. A photo-patterning process is successfully conducted for security printing application in materials science.
关键词： lanthanide complexes,single-crystal-to-single-crystal transformation,security printing,UV irradiation,photoluminescent
更新于2025-09-16 10:30:52
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Comparison of spectral and thermal properties and antibacterial activity of new binary and ternary complexes of Sm(III), Eu(III) and Gd(III) ions with N-phenylanthranilic acid and 1,10-phenanthroline
摘要： New binuclear binary and ternary complexes of Sm(III), Eu(III), and Gd(III) ions with N-phenylanthranilic acid and 1,10-phenanthroline were obtained in solid phase and characterized by chemical and elemental analysis, molar conductance, UV–VIS and IR spectroscopies as well as thermoanalytical techniques (TG/DTG–DSC coupled with MS and FT-IR). The dilution method was used to examine the antibacterial activity of the synthesized compounds. The spectroscopic studies indicated that the carboxylate group of N-phenylantranilate ligand is involved in the coordination of metal ion, both in binary and ternary complexes. Thermal decomposition of the obtained compounds was carried out in air and nitrogen atmosphere. During heating, the complexes decompose via intermediate products to the oxide (Ln2O3) in air atmosphere and to the oxide (Ln2O3) or oxide polluted by carbon (Ln2O3+nC) in nitrogen atmosphere. The dehydration process was discussed in relation to the nature of water present in these compounds. Using coupled TG–FTIR–MS techniques the decomposition pathways of the synthesized compounds were examined. Additionally, gaseous products released during pyrolysis and thermal oxidation of the complexes were identified. All the complexes exhibit marked activity against two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and one Gram-positive (Staphylococcus aureus) bacterial strains. The ternary complexes, especially Gd(III) complex in comparison with the binary ones, have enhanced activity against Escherichia coli. Moreover, antibacterial activity of the synthesized compounds with respect to Pseudomonas aeruginosa is comparable to tetracycline and greater than for kanamycin, erythromycin, and ampicillin.
关键词： 1,10-phenanthroline,Thermal analysis,Lanthanide complexes,N-phenylanthranilic acid,EGA
更新于2025-09-11 14:15:04
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White-Light Emitting Di-Ureasil Hybrids
摘要： White-light emitting materials have emerged as important components for solid state lighting devices with high potential for the replacement of conventional light sources. Herein, amine-functionalized organic-inorganic di-ureasil hybrids consisting of a siliceous skeleton and oligopolyether chains codoped with lanthanide-based complexes, with Eu3+ and Tb3+ ions and 4,4'-oxybis(benzoic acid) and 1,10-phenanthroline ligands, and the coumarin 1 dye were synthesized by in situ sol–gel method. The resulting luminescent di-ureasils show red, green, and blue colors originated from the Eu3+, Tb3+, and C1 emissions, respectively. The emission colors can be modulated either by variation of the relative concentration between the emitting centers or by changing the excitation wavelength. White light emission is achieved under UV excitation with absolute quantum yields of 0.148 ± 0.015, 0.167 ± 0.017, and 0.202 ± 0.020 at 350, 332, and 305 nm excitation, respectively. The emission mechanism was investigated by photoluminescence and UV–visible absorption spectroscopy, revealing an efficient energy transfer from the organic ligands to the Ln3+ ions and the organic dye, whereas negligible interaction between the dopants is discerned. The obtained luminescent di-ureasils have potential for optoelectronic applications, such as in white-light emitting diodes.
关键词： lanthanide complexes,di-ureasil organic–inorganic hybrids,in situ sol–gel synthesis,white light emission,coumarin 1
更新于2025-09-10 09:29:36
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Two novel Sm(III) complexes with different aromatic carboxylic acid ligands: Synthesis, crystal structures, luminescence and thermal properties
摘要： Two novel Sm(Ⅲ) complexes, [Sm(3,4-DMBA)3(3,4-DMHBA)(5,5′-DM-2,2′-bipy)]2 (1), [Sm(3-MOBA)3(5,5′-DM-2,2′-bipy)]2 (2) (3,4-dimethylbenzoic acid = 3,4-DMHBA, 3-methoxybenzoic acid = 3-MOHBA and 5,5′-dimethyl-2,2′-bipyridine = 5,5′-DM-2,2′-bipy), have been successfully synthesized and assembled. The crystal structures were determined by single crystal X-ray diffraction. Two complexes were characterized by the elemental analysis, IR, powder X-ray diffraction, thermal gravimetric technology. Because of the different ligands, the structures of the two complexes are very different, especially the structure of the complex 1. Each central Sm(Ⅲ) ion of complex 1 was coordinated by three deprotonated 3,4-DMBA-,one unprotonated 3,4-DMHBA and one 5,5′-DM-2,2′-bipy, which has rarely been reported before. However each central Sm(Ⅲ) ion of complex 2 was only coordinated via three deprotonated 3-MOBA- and one 5,5′-DM-2,2′-bipy. In addition, the thermal decomposition mechanism and the three-dimensional infrared accumulation spectra of the evolved gas during the thermal decomposition for two complexes were studied by the simultaneous TG/DSC-FTIR technology. What′s more, the luminescence properties of two complexes were also discussed. Finally, the bacteriostatic activities of two complexes were evaluated against Staphlococcus aureus, Escherichia coli and Candida albicans.
关键词： TG/DSC-FTIR,Crystal structure,Bacteriostatic activities,Lanthanide complexes,luminescence
更新于2025-09-10 09:29:36